desktop: add Russian translations

[wehrwolfmann]

The launcher entry is the only string of the Kernel Manager a user sees before starting it, and it is still English on a Russian desktop even though the app itself has a complete Russian catalogue in lang/. In the menu it reads "CachyOS Kernel Manager / Manage kernels" while everything around it is Russian.

This adds Name[ru], GenericName[ru], Comment[ru] and Keywords[ru] next to the existing Italian and Japanese lines, same style, nothing else touched. Wording follows the terms already used in cachyos-kernel-manager_ru.ts (ядро for kernel), and CachyOS stays in Latin as a product name.

Keywords[ru] keeps the original cachyos;system;kernel; in front of the Russian words on purpose — a Keywords[ru] line replaces the untranslated one rather than adding to it, so dropping the Latin keywords would break searching for "kernel" in a Russian session. The Japanese line does the same.

desktop-file-validate is clean.

[wehrwolfmann]

Unrelated to this PR, but you may want to know: the PR Labeler workflow fails on every pull request, including this one.

The config file was not found at .github/labeler.yml
##[error]HttpError: Not Found

.github/workflows runs actions/labeler@v4 with configuration-path: .github/labeler.yml, but that file is not in the repository, so the job dies in about 5 seconds no matter what the PR touches. It has presumably been red for a while, which makes the red cross on a PR meaningless — that is the part I would find annoying as a maintainer.

Either add the config or drop the workflow; both take a minute. Not something I want to fix inside a translation PR, so just flagging it.